Successful re-ossification of calvarial defects is characteristically limited to immature animals and children less than 1-2 years of age. Conversely, skeletally mature animals demonstrate an almost universal inability to heal even small trephine defects, with bone deficits remaining present for the life of the subject. While a plethora of strategies have been developed over the past century for treating adult calvarial defects, the myriad of methods currently available reflects the inadequacies of each therapeutic technique. By combining advances in developmental biology, organogenesis, stem cell biology, bioengineering, and material sciences, however, a new paradigm for calvarial bone tissue engineering has emerged- regenerative medicine. Of the multitude of applications for tissue engineering and regenerative medicine, calvarial defects represent one of the most likely targets to meet with clinical success, given the alluring potential for implementation of translational therapies in the near future. This proposal seeks to determine the optimal design of a calvarial regenerative strategy utilizing human adipose-derived stromal cells (ASCs). In Specific Aim 1, we will use RNAi-mediated suppression of BMP antagonism to enhance in vitro osteogenesis. In Specific Aim 2, we will assay the ability of these cells to regenerate bone in vivo in our critical- sized calvarial defect nude mouse model. We will employ the use of biodegradable apatite-coated poly(DL-lactic-co-glycolic acid) (PLGA) scaffolds to deliver the cells and determine if skeletal healing can be augmented by modulating BMP signaling via RNA interference of Noggin. We will also be able to examine the respective contributions of the implanted donor and surrounding host cells to the regenerate. Ultimately, the translational goal of this application is to determine a cell-based regenerative medicine strategy to repair calvarial defects using tissue engineered bone. Project Narrative: Adult animals demonstrate an almost universal inability to heal even small skull defects, with bone deficits remaining present for the life of the subject. While many strategies have been developed over the past century for treating adult skull defects, the myriad of methods currently available reflects the inadequacy of each therapeutic technique. By combining advances in developmental biology, organogenesis, stem cell biology, bioengineering, and material sciences, however, a new paradigm for bone tissue engineering has emerged- regenerative medicine. Of the multitude of applications for tissue engineering and regenerative medicine, adult skull defects represent one of the most likely targets to meet with clinical success, given the alluring potential for implementation of translational therapies in the near future. This proposal seeks to elucidate a skull regenerative strategy utilizing human fat cells.